Air Conditioner Filter Cleaning

air conditioner filter cleaning
Air conditioner filter and air handler

Air conditioner Filter cleaning rids dust off your AC sieve.

The air filter’s work is to clean the indoor air that you breathe. It does that by straining particulates found in the conditioned room’s air.

An air conditioner installed with a technical precision should serve you for years before any major breakdown. You only need to do minor routine maintenance that your AC manufacturer recommends. One of these regular maintenances is air conditioner filter cleaning, or changing the air filter in the case of a disposable filter.

If you don’t clean or change the air filter at the right time, your AC’s cooling efficiency will downgrade.

Suppose your AC has been performing well. Suddenly, you notice a glitch like “no cooling from your indoor unit. Or, the cooling becomes inefficient.” Such anomaly could be an underlying filter related-fault. Using your AC for long without giving it necessary maintenance can cause such a fault.

If you’re the AC owner and you have HVAC expertise, it’s easy to diagnose and work on your AC. But if you don’t have the skill, little ambition is enough for you to handle some DIY fixes.

However, if you are less interested in the hands-on aspect of service and maintenance, read on to learn a thing or two about your air conditioner filter cleaning. It’s resourceful to have a rough idea of the work an AC technician would do on your machine.

So let’s look into the faults that can require air conditioner filter cleaning, to solve.

Lack of air conditioner filter cleaning can result in inefficient or no cooling.

The cooling effect of an AC happens at the air conditioner evaporator tube. The evaporator tube is also called indoor heat exchanger. It is bundled in one unit called Indoor Unit (shown below).
AC indoor unit
An indoor unit that holds the air filter
The indoor unit of a ductless split AC is installed in the conditioned room. But a Central Air Conditioner’s evaporator is in the Air Handling Unit that sits outside the conditioned room. Many Central AC designs place the AHU in the basement or attic. In houses without a basement or spacious attic, it sits in a convenient spot outside the conditioned rooms.
In a ducted system, the evaporator fan draws air from the conditioned room via the return side of the duct. AC air filter cleans the air before it reaches the evaporator coil surface. The evaporator fan pushes clean low-temperature air through the duct. Nothing but clean air should flow across the evaporator fins.
After your AC has run for one to three months, dirt and dust accumulate on the filter. This dust clogs the filter. The clogging can happen sooner or later than three months, though. It depends on how clean your environment is. Smoggy and dusty environment means the filter gets dirty sooner.
Then the time for filter cleaning or changing comes. To understand how important this maintenance measure is, compare it with changing your car’s air filter. What do you think would transpire if you don’t change your car’s air filter according to your vehicle manufacturer’s recommendation? Your engine will choke.
Likewise, if you don’t clean or change the AC filter, air circulation will be impaired. And although you’ll be running your AC for longer hours, you’ll still experience reduced cooling. A clogged filter can also lead to icing of evaporator tubing.
So if you experience reduced cooling, first check the AC air filter.

Air Filter

The air filter is an element of AC that eliminates foreign particles from the air you breath. It has tiny pores that allow air molecules through but blocks dust and dirt from reaching the evaporator tube surface.

In a ductless split-phase air conditioner, the air filter is in the indoor unit. But in a duct system AC, it’s within the Air Handling Unit assembly.

The two types of filters are reusable and disposable filters. When you service your AC, you clean and use again reusable filters, but throw away disposable filters.

The degree of filtration defines the quality of a filter, and the quality of a filter defines its price. A medical filter used by individuals with allergies costs higher than a normal filter.

Dust and dirt sieved by the filter form a layer on the filter after weeks of operation. This dust blocks filter pores and hinder free air flow. The resultant effect of this phenomenon is impaired airflow across the filter and evaporator coil. Eventually, there’ll be no sufficient cool air coming from the indoor unit; not until you clean the filter.

Let me explain the simple air conditioner filter cleaning procedure using the photo below:

AC Air filter
Indoor unit with washable air filter

Before cleaning the filter, switch off the AC at the wall switch or use interface remote control.

  1. Pry the front evaporator cover open. A split indoor unit has a pair of reusable filters. In my example photo above, it’s a washable fine plastic gauze.

  2. Pull the filters out. If the AC has operated for one to three months without cleaning the filter, it’s now full of dust and dirt.

  3. Use a hand blower (if available) to blow off the dust from the filter, then scrub it with a soft brush in soapy water. Put it out in the sun to dry before you insert it back into the indoor unit.

  4. As the filter dries out, you’d want to find out if the indoor unit has gathered dust hidden in inaccessible joints – in most cases, there is concealed dust and dirt.
    Use a portable vacuum cleaner (with nozzle) to suck up the hidden dust.

Ductless split AC filter
Air filter of a ductless AC
Duct AC air filter
Air filter of an AC with a duct system


The two procedures for cleaning or replacing ductless or ducted AC systems don’t differ much. A duct system has its filter secured in place with screws at the AHU. Locate the screws, unscrew, and remove the filter. Clean and put back, or replace if it’s a disposable filter.

If you ignore air conditioner filter cleaning, it compounds filter-related problems. Your AC electricity consumption will rise. That’s not good news because your cooling system already accounts for nearly 50% of your home power consumption when it’s functioning normally.